Method and device for processing a signaling message related to a communication service of a client device

1. A method, implemented in a communication network comprising a mobile switching center, for processing signaling messages relating to a communication service provided to a client device by the communication network, the method comprising: performing the following acts by the mobile switching center in response to the client device being connected to the communication network via an access network operating in circuit mode: translating a first signaling message, designed to be routed via the access network operating in circuit mode, into a second signaling message designed to be routed via an access network operating in packet mode, and vice versa, and performing the following acts by the mobile switching center in response to the client device being connected to the communication network via an access network operating in packet mode: receiving from said client device a third signaling message designed to be routed via the access network operating in packet mode, replacing in a source address field of the received third signaling message, an address of the client device with an address of the mobile switching center to produce a modified third signaling message, sending said modified third signaling message to a server of the communication network, receiving from the server of the communication network a fourth signaling message designed to be routed via the access network operating in packet mode, replacing in a recipient address field of the received fourth signaling message, the address of the mobile switching center with the address of the client device to produce a modified fourth signaling message, and sending said modified fourth signaling message to said client device.

2. The method as claimed in claim 1 , the method further comprising: during a phase of associating the client device with said access network operating in packet mode in order to access said communication network, the client device acquiring the address of the mobile switching center of the communication network, from an access network mobility management device.

3. The method as claimed in claim 1 , further comprising, during the phase of associating the client device with the access network operating in packet mode: receiving, by the access network mobility management device, a request to associate with said access network, from the client device, following authentication of the client device by the mobility management device, the access network mobility management device sending, to said client device, an address based on the Internet protocol IP and assigned to said client device and the address of the mobile switching center of the communication network designed to receive, from the client device, at least one signaling message relating to the communication service provided to said client device by the communication network.

4. The method as claimed in claim 3 , wherein the address of the mobile switching center is sent to the client device in the case where the client device is connected to a communication network termed a visited network, the visited network being a communication network different from a network of the operator to which the client device subscribes.

5. The method as claimed in claim 4 , wherein the address of the mobile switching center is sent to the client device in the case where the mobility management device receives, from a client database of a communication network termed a nominal network, an item of information indicating that the nominal network is not suitable for managing a situation of handing over the connection of the client device from an access network operating in packet mode to an access network operating in circuit mode, or vice versa, the nominal network being a communication network of the operator to which the client device subscribes.

6. The method as claimed in claim 1 , wherein the first and third and fourth signaling messages are messages in accordance with the SIP protocol, included in the following list: a message REGISTER to register the client device, a communication request message INVITE sent by the client device to another terminal, a message SUBSCRIBE to subscribe to an events notification service, sent by the client device to a server, a state publication message PUBLISH sent by the client device to a server, a message MESSAGE sent by the client device to another terminal or server, a message for exchanging communication capabilities, sent by the client device to another terminal.

7. A processing device for processing a signaling message relating to a communication service provided to a client device by a communication network, said device comprising: a processor; and a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the processing device to: in response to the client device is-being connected to the communication network via an access network operating in circuit mode: translate a first signaling message, designed to be routed via the access network operating in circuit mode, into a second signaling message designed to be routed via an access network operating in packet mode, and vice versa, in response to the client device being connected to the communication network via an access network operating in packet mode: receive from said client device a third signaling message designed to be routed via the access network operating in packet mode, replace in a source address field of the received third signaling message, an address of the client device with an address of the processing device to produce a modified third signaling message, send said modified third signaling message to the server of the communication network, receive from the server of the communication network a fourth signaling message designed to be routed via the access network operating in packet mode, replace in a recipient address field of the received fourth signaling message, the address of the processing device with the address of the client device to produce a modified fourth signaling message, and send said modified fourth signaling message to said client device.

8. The processing device as claimed in claim 7 , wherein the instructions further configure the processing device to: receive and transmit a media data stream relating to a communication set up between said client device and another client device, replace, in a source address field of the media data stream, the address of the client device with the address of the processing device when the media data stream is received from the client device and destined for the other client device, replace, in a recipient address field of the media data stream, the address of the processing device with the address of the client device when the media data stream is received from the other client device and destined for the client device.

9. The processing device as claimed in claim 7 , furthermore comprising a memory storing an address of a proxy server of the subsystem of the communication network.

10. A mobile switching center comprising the processing device as claimed in claim 7 .

11. A system comprising: a processing device for processing a signaling message relating to a communication service provided to a client device by a communication network, said processing device comprising: a first processor; and a first non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the first processor configure the processing device to: in response to the client device being connected to the communication network via an access network operating in circuit mode: translate a first signaling message, designed to be routed via the access network operating in circuit mode, into a second signaling message designed to be routed via an access network operating in packet mode, and vice versa, in response to the client device being connected to the communication network via an access network operating in packet mode: receive from said client device a third signaling message designed to be routed via the access network operating in packet mode, replace in a source address field of the received third signaling message, an address of the client device with an address of the processing device to produce a modified third signaling message, send said modified third signaling message to the server of the communication network, receive from the server of the communication network a fourth signaling message designed to be routed via the access network operating in packet mode, replace in a recipient address field of the received fourth signaling message, the address of the processing device with the address of the client device to produce a modified fourth signaling message, and send said modified fourth signaling message to said client device; and the client device, which comprises: a second processor; and a second non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the second processor configure the client device to: acquire the address of the processing device, from an access network mobility management device, during a phase of associating the client device with the access network operating in packet mode in order to access said communication network.

12. The system as claimed in claim 11 , wherein the first and third signaling messages are messages in accordance with the SIP protocol, included in the following list: a message REGISTER to register the client device, a communication request message INVITE sent by the client device to another terminal, a message SUBSCRIBE to subscribe to an events notification service, sent by the client device to a server, a state publication message PUBLISH sent by the client device to a server, a message MESSAGE sent by the client device to another terminal or server, a message for exchanging communication capabilities, sent by the client device to another terminal.

13. The system as claimed in claim 11 , further comprising: an associating device for associating the client device with the access network operating in packet mode, in order to access the communication network, the associating device comprising: a third processor; and a third non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the associating device to: receive a request to associate with said access network operating in packet mode, from the client device, authenticate the client device, send, to said client device, an address based on the Internet protocol IP and assigned to said client device and the address of the processing device of the communication network designed to receive, from the client device, at least one signaling message relating to the communication service provided to said client device by the communication network.